1. Field
The presently disclosed subject matter relates to a semiconductor light source apparatus and a lighting unit using the semiconductor light source apparatus, and more particularly to a semiconductor light source apparatus that can change a color tone and a lighting unit that can also emit a large amount of light intensity while it can change a color tone in order to be able to use for a stage light, a street light, a projector, a vehicle light, a spot light, etc.
2. Description of the Related Art
Recently, semiconductor light source devices such as an LED and the like have been used as a light source for a lighting unit. By using characteristics of the semiconductor light source devices, a light source and a lighting unit that can emit various color lights have been developed. A light source and a lighting unit that can change a light-emitting color by using three kinds of LEDs, a red LED, a green LED and a blue LED are disclosed in Patent Document No. 1 (Japanese Patent Application Laid Open JP2004-055360).
The light source disclosed in Patent Document No. 1 may emit various light-emitting colors by controlling each of light intensities of the three LEDs. However, because it is physically impossible to locate the three LEDs at the same position, each of the three LEDs is located at an appropriate interval with respect to each other. Accordingly, when the light source is used for a lighting unit such as a spot light that controls a light distribution via a lens, a color variation may occur around a light distribution pattern because each of the three LEDs is located at a different position, that is, because each optical axis of the three LEDs is different.
In order to improve such a color variation, a light source apparatus using a phosphor wheel that may be used as a light source for projectors such as an overhead projector is disclosed in Patent Document No. 2 (Japanese Patent Application Laid Open JP2004-341105). FIG. 1a is a schematic structural view showing a conventional light source apparatus using a phosphor wheel that is disclosed in Patent Document No. 2 and FIG. 1b is a schematic front view showing the phosphor wheel that is used in the conventional light source apparatus.
The conventional light source apparatus includes the phosphor wheel 91; a motor 94 rotating the phosphor wheel 91; and a semiconductor light source 95 such as a laser diode emitting ultraviolet light. The phosphor wheel 91 includes a red phosphor layer 92a, a green phosphor layer 92b and a blue phosphor layer 92c on a transparent substrate such as a silica glass substrate so that each area of the phosphor layers 92a, 92b and 92c is equally divided by boundary lines 93a, 93b and 93c, which intersect with a rotational axis of the phosphor wheel 91. The semiconductor light source 95 is located adjacent to the phosphor wheel 91.
When the phosphor wheel 91 is rotated at a high speed (e.g. 3,600 rpm) by the motor 94, the red phosphor layer 92a, the green phosphor layer 92b and the blue phosphor layer 92a are excited by the ultraviolet light emitted from the semiconductor light source 95, and therefore the semiconductor light source 95 may emit white light via the phosphor wheel 91 due to an additive color mixture. In this case, because the semiconductor light source 95 can emit the ultraviolet light toward the phosphor wheel 91 at a specific position, the conventional light source apparatus may prevent the semiconductor light source 95 from causing a color variation around a light distribution pattern.
The above-referenced Patent Documents are listed below and are hereby incorporated with their English abstracts in their entireties.
1. Patent document No. 1: Japanese Patent Application Laid Open JP2004-055360
2. Patent document No. 2: Japanese Patent Application Laid Open JP2004-341105
However, although the conventional light source apparatus using the phosphor wheel 91 may prevent color variation, it may not be able to adjust a color tone of light emitted from the semiconductor light source 95. The color tone may be adjusted by preparing each phosphor wheel of the three phosphor layers 92a, 92b and 92c and by controlling each rotation speed of the phosphor wheels of the three phosphor layers 92a, 92b and 92c. 
However, it may be difficult to control the respective rotation speeds of the phosphor wheels when at a high speed. In addition, three motors may be required and also a complex controller may be required to control the three motors. Moreover, in the above-described light source apparatus using the phosphor wheel 91, a color breakup may occur although the color variation may be avoided. The color breakup means a phenomenon such that each of red light, green light and blue light are instantaneously recognized in a repetitive manner instead of white light.
When the light source apparatus using the phosphor wheel is used in a normal room, the color breakup may not occur. When the light source apparatus is used in a dark room and when suddenly withdrawing the human eye from a light-emitting spot of the light source, a color breakup may occasionally occur. The color breakup may cause fatigue to the human eye. If the phosphor wheel is rotated at a very high speed, although the color breakup may be almost prevented, sound generated from the motor may increase.
The disclosed subject matter has been devised to consider the above and other problems, characteristics and features. Thus, an embodiment of the disclosed subject matter can include various semiconductor light source apparatuses which can adjust a color tone of white light and can prevent the color breakup of the white light. In this case, the color tone can be adjusted by a structure that includes a moving module for changing a distance between an intersection of an optical axis of a light source and a phosphor wheel and a rotation axis of the phosphor wheel, which thus varies a ratio of mixing lights for the white light according to distance. In addition, a high power LED can be used as the light source due to a radiation effective by a rotation of the phosphor wheel. Thus, the semiconductor light source apparatus can adjust a color tone of an illumination light having a large amount of light intensity, and therefore can be employed for various lighting units such as a projector, a stage light, a street light, general lighting, etc.